Printing mechanism for serial data recording

ABSTRACT

A serial printing mechanism with a constantly rotating type lever assembly in which the type lever selected for printing performs, within a predetermined angular range, a printing movement directed towards the axis of rotation. The type lever assembly in the form of a rim-shaped magazine rotates immediately in front of the printing point, the axis of rotation extending vertically to the printing point. The respective type lever selected for printing performs a printing movement directed inwardly towards the axis of rotation. Approaching said axis of rotation asymptotically, printing is effected exactly on the axis of rotation or in its immediate vicinity.

United States Patent [1 1 Fleischer Oct. 30, 1973 PRINTING MECHANISM FORSERIAL DATA RECORDING [75] Inventor: Manfred Fleischer, Pforzheim,

Germany 22 Filed: Apr. 12, 1971 21 Appl.No.: 132,946

[30] Foreign Application Priority Data 3,289,805 12/1966 Kleinschmidt eta1. 197/18 3,355,001 11/1967 Reed et al 197/18 3,356,199 12/1967Robinson 197/54 3,417,847 12/1968 Fleischer et al. 197/18 3,420,3491/1969 Kurfmuller 197/18 X 3,542,182 11/1970 Langenberger 197/183,615,000 10/1971 Galaske 6! al. 197/18 FOREIGN PATENTS OR APPLICATIONS414,694 12/1966 Switzerland 197/18 Primary Examiner-Edgar S. BurrAttorneyC. Cornell Remsen, Jr., Walter J. Baum, Paul W. Hemminger,Charles L. Johnson, Jr., Philip M. Bolton, Isidore Togut, EdwardGoldberg and Menotti J. Lombardi, Jr.

[57] ABSTRACT A serial printing mechanism with a constantly rotatingtype lever assembly in which the type lever selected for printingperforms, within a predetermined angular range, a printing movementdirected towards the axis of rotation. The type lever assembly in theform of a rim-shaped magazine rotates immediately in front of theprinting point, the axis of rotation extending vertically to theprinting point. The respective type lever selected for printing performsa printing movement directed inwardly towards the axis of rotation.Approaching said axis of rotation asymptotically, printing is effectedexactly on the axis of rotation or in its immediate vicinity.

7 Claims, 4 Drawing Figures PRINTING MECHANISM FOR SERIAL DATA RECORDINGBACKGROUND OF THE INVENTION The present invention relates to a printingmechanism for serial data recording in which the printing unit consistsof a type lever magazine arranged in a rimshaped manner in relation tothe axis of rotation and which rotates at constant speed, and in whichthe individual type levers selected for printing are caused to perform aprinting movement towards the axis of rotation within a predeterminedangular range via a cam arrangement.

A printing mechanism of this kind is described in U.S. Pat. No.3,417,847 and U.S. Pat. application Ser. No. 754,578 now allowed, bothassigned to the assignee of this invention. In the embodiments describedthere, there is provided a plate-shaped type lever magazine horizontallyrotating below the printing platen, from which the selected type leversare lifted in the direction of the axis of rotation and strike theplaten.

By the arrangement of the plate-shaped type lever magazine below theplaten, virtually only web-type and sheet recording media can be usedbecause the position of the type lever magazine requires that therecording medium be led around the platen.

In many cases, however, it is necessary to letter stiff recording mediasuch as ledger cards or savings bank pass books which are difficult tobend. In such cases an arrangement is required which permits a straightguidance of the recording medium.

A printing mechanism which meets this requirement is disclosed in U.S.Pat. No. 3,289,805. Here also a constantly rotating type lever magazineis provided which, however, is designed in the manner ofa cage and, inrotating around a vertical axis, is arranged before the platen. Therespective type lever selected for printing strikes outwardly and hitsthe platen at the moment it passes the printing point.

This conventional printing mechanism is disadvantageous in that, due tothe volume of the basket increasing with the number of type levers, thenumber available for printing is limited depending on the rotationalspeed because, in order to achieve a clean print, a certain relativevelocity between the stationary recording medium and the circulatingtypes must not be exceeded.

Another printing mechanism meeting the abovementioned requirements isdisclosed in U.S. Pat. 2,833,387. Here the stationary assembly of typelevers is grouped in the manner of a basket around the central axis ofthe printing unit arranged vertically in relation to the printing point,the type levers being pivoted in such a manner that, hitting inwardly,they strike on the extension of the central axis.

Apart from the conventional type lever selection and print control whichenable only a relatively low sequence of characters, this arrangementhas the very significant disadvantage that, as a result of the typelevers being stationary, each printing type must be solderedon in adifferent angle in order to achieve upright print- SUMMARY OF THEINVENTION The above-mentioned disadvantages of these conventionalprinting mechanisms are avoided by the printing mechanism according tothe invention, which is characterized in that the type lever magazinerotates in parallel to and closely before the printing point, wherein inthe normal path of rotation, the type levers assume a position pointingaway from the printing point, wherein the respective type lever selectedfor printing performs a printing movement directed asymptoticallytowards the axis of rotation, and wherein printing is effected wheneverthe respective type lever stands vertically over the printing point.

Using the inventive printing mechanism, it is possible on the one handto print stiff recording media, and on the other hand, to double thenumber of characters without any appreciable changes of conditions atthe moment of printing. In addition, all type levers may be provided ina conventional manner with unidirectional types.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described inmore detail with reference to two embodiments thereof in conjunctionwith the accompanying drawings in which:

FIG. 1 is a schematic cross-sectional view of a printing mechanismaccording to the invention taken along line I I of FIG. 2;

FIG. 2 is a front view of the printing mechanism of FIG. 1, with thecover portion being shown as if it were transparent;

FIG. 3 is a partial view of the shape of the printing cam; and

FIG. 4 shows a modification differing with respect to the relativeposition of the printing unit of FIG. 1 in relation to the platen.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) In the printing mechanismaccording to the invention as shown schematically in FIG. 1, theprinting unit 1 comprises on the one hand a pot-like body of revolution2 provided with a hollow shaft butt 2a and, on the other hand, a cover 3shielding the body 2, in which, pivoted on an annular axle 5, typelevers 4 are held in radial guide slots 3a. The cover 3 having a centricopening 3c is permanently connected with the body 2 in a manner notshown.

The printing unit 1 is rotatably mounted for example in a pillow block 9of a carriage device (not shown) via which, in known manner, theprinting unit 1 is guided in stepped fashion or continuously along aprinting base.

This printing base may be a printing platen 13 with a curved surface ora plane printing rail. In each case, the printing unit 1 is arranged sothat the axis of rotation extends vertically in relation to the printingpoint, i.e. as shown, the line of print and the platen are horizontal,with the axis of rotation of the printing unit being also horizontal butperpendicular to the line of print and the printing platen 13.

The distance between the printing base, i.e., the platen 13 in theembodiment of FIG. 1, and the front surface 3d of the cover portion 3 isexactly such as to insure that the recording medium (media) 14 can beinserted without hindrance, and that there is a certain safety distancebetween the recording medium and the front surface 3d.

The printing unit 1 is rotated via a toothed-gear drive l1, 12 by auniformly driven splined shaft 10.

In the normal (rest) condition, the type levers 4 mounted in the cover 3rest on a concentric track 3b against which they are held during therotation of the printing unit 1 by the effective centrifugal force.

Supported in the pot-like body of revolution 2 is a cam unit 6 which isguided by a shank 6e slidably supported in the hollow shaft butt 2a.This shank 6eprojects beyond the shaft butt 2a which is flush with thepillow block guide. Stationarily arranged at this free end is aflange-like adjusting ring 8 resting flatly against the pillow block 9.Via an eccentric device 8a shown only symbolically, the adjusting ring 8can be twisted within certain limits against the pillow block 9. Thus,it is accomplished that the cam unit 6, unlike the other parts of theprinting unit 1, is stationary and can be adjusted from outside via theeccentric device 8a.

The cam unit 6 serves on the one hand to secure the type levers 4 intheir normal path of rotation and, on the other hand, to lead the typelevers 4 selected for printing to the printing point and back to thepath of rotation.

To this end, the unit 6 has a ring-shaped guideway 6a (FIG. 2) by whichthe type levers 4, in connection with the type lever support (i.e.concentric track) 3b, are positively guided. This kind of guidance isnecessary because, if at rest, i.e., rotational motion has ceased forexample in a stepped motion operation, the type levers 4 of the upperrange, i.e., those winding up in a position at the top most part of theprint unit 1, which otherwise would norm ally be held against the track3b by the centrifugal force of the rotating printing unit, would falltowards the center. If the printing mechanism were restarted, this wouldinevitably result in destruction of the printing unit unless measuresare taken such as ring-shaped guide 6a.

As shown, the guideway 6a is interrupted in the lower part of FIG. 2. Atthis point, permanently connected to the cam unit 6, there is arranged aselecting station 7 designed, for example, according to the US. Pat.application Ser. No. 828,176, filed May 27, 1969, by which the typelevers 4 intended to perform printing are magnetically lifted out of thenormal path of rotation. In the course of printing unit rotation, theselected type lever 4 is finally deflected as illustrated in FIG. 1 bythe dotted type lever 4, whereby its free end is moved into the range ofa cam 6b leading the type lever 4 to the printing point. This printingcam is designed so that, in an angle of rotation of about 160 from theselecting point, the respective type lever performs a movement directedasymptotically towards the axis of rotation of the printing unit 1. As aresult, the type lever 4 is accelerated to a final velocity which isdetermined by the required printing energy. Shortly before therespective type lever 4 stands vertically over (in front of) theprinting point i.e., the point on the line of print at which theselected type lever strikes the platen (FIG. 2), the printing cam 6bends, so that the type lever covers the last distance to the striking ofthe type 4a against the recording medium 14 in free flight. Strikingtakes place exactly at the instant the type lever stands vertically overthe printing point, as shown in FIG. 2. In the embodiment shown in FIGS.1 and 2, the printing point lies exactly on the extended axis ofrotation of the printing unit 1, the selected type lever having its freeend pass through the center of rotation of the printing unit to arriveat the printing point. Thereby, even if the rotational speed of theprinting unit 1 is very high, the

movement of the type 4a relative to the recording medium 14 ispractically zero so that clean printing is insured in each case. I

During further rotation, the type lever 4, in rebounding after theprinting, is caught by a resetting cam 60 and forcibly reset to thenormal path of rotation. The schematic representation of FIG. 2 showsonly one of the required two cam surfaces effecting a positive resettingforce on a selected type lever.

For clarity and since the principle of such forced guidances iswell-known, the second cam has been omitted in FIG. 2.

In reset area of a recess 6d, the resetting cam 6c joins the guideway 6aby which the respective type lever 4 is rest to the normal path ofrotation. Via a guideway section 6a subsequently arranged in thedirection of rotation, a forced guidance is effected again in connectionwith the type lever support 3b (FIG. 1), whereby it is insured that therespective type lever 4, stably enters the area of the selecting station7 for a possible new selection.

As can best be seen from FIG. 1, the shank 6e is provided with alongitudinal bore hole 6f through which the control lines of theselecting station 7 (not visible in FIG. 1) are lead outwardly.

In a cross-section through FIG. 1, the partial view of FIG. 3 showsessentially the cam unit 6 and specifically the design of the printingcam 6b. In order to obtain a favourable, i.e. not too steep curvature ofthe cam, the track on which the type levers slide is designed so thatthe cam 6b engaging the free end of the type lever at the beginning hasa curvature directed more closely towards the fulcrum of the type levers4, as shown in FIG. 3. Thus, the cam can be made flatter. At the sametime, the force components acting upon the respective type levers assumefavourable values. In addition, the abrasion of the type levers slidingon the curved track is distributed over a greater area, so that wear isminimized.

The resetting curve 6c is designed correspondingly, except that, inaccordance with its function, it engages the middle of the type lever atthe beginning and acts upon the free end of the type lever 4 towards theend, i.e., with the transition into the guideway 6a.

FIG. 4 shows schematically a modified form of the embodiment describedso far.

As already mentioned and as is well-known, in type lever printingmechanism, a relative movement between the recording medium and theprinting type is allowed up to a speed of about 3 m/sec.without'resulting in any noticeable reduction in the printing quality.

In the embodimentshown in FIG. 4, using this effect, printing is nolonger performed on the extended axis of rotation of the printing unitbut above this axis at a distance 1:. For the quantity of x, thefollowing relation applies:

x V n where V is the permissible relative velocity in mm/sec. betweentype 4a and recording medium 14 at the moment of printing, and n is theconstant rotational speed in r.p.m. By this measure, the radius of theannular axle 5 can be increased by the distance x with the length of thetype levers remaining unchanged. Thus, compared to the embodiment shownin FIG. 1, a correspondingly greater number of type levers can beaccomodated within a type lever assembly, with the limiting effect beingprimarily determined by the radially extending guide straps between theindividual type levers, which, for reasons of strength, must not fallbelow a certain thickness in the direction of the axis of rotation.

What is claimed is:

1. A printing mechanism for serial data recording comprising:

a platen;

a printing point disposed in a given plane tangential to said platen;and

a printing unit including a pot-shaped body of revolution having a firsthollow shaft extending therefrom in a direction away from said printingpoint and a cover for said body of revolution opposite said first shaftadjacent said printing point,

means coupled to said first shaft to rotate said first shaft, said bodyof revolution and said cover about an axis of rotation disposedperpendicular to said given plane,

a plurality of type levers disposed within said cover for rotationtherewith, each of said type levers having one end that is free formovement toward said printing point carrying type to be printed and theother end is pivotably mounted to said cover in a spaced radialrelationship with said axis of rotation,

an opening in said cover disposed coaxial of said axis of rotation andin a printing relationship with said printing point and said one end ofeach of said levers, and p a cam unit means disposed within said body ofrevolution in a cooperative relation with said one end of each of saidtype levers to control the movement thereof so that a selected one ofsaid type levers is moved first toward said axis of rotation and thenpasses through said opening parallel to said axis of rotation to strikesaid printing point perpendicular to said given plane to effect aprinting at said printing point,

said cam unit means being adjustably mounted within said first shaft bymeans of a second hollow shaft.

2. The printing mechanism according to claim I wherein said coverincludes guide slots directed radially to said axis of rotation forguiding said type levers through said opening, and a type lever supporttrack disposed concentrically about said axis of rotation formaintaining said type levers in a normal rotating position.

3. The printing mechanism according to claim 1 wherein said cam unitmeans includes a guideway concentrically disposed about said axis ofrotation, a printing cam and a resetting cam, each of said printing camand said resetting cam acts upon said one end of each of said typelevers in cooperation with said guideway to effect a printing ofaselected lever, said guideway being interrupted only at a givenlocation to enable type lever selection.

4. The printing mechanism according to claim 3 wherein a selectingstation is provided at said given location for selecting desired ones ofsaid type levers, and wherein control lines to said selecting stationare led through said second shaft.

5. The printing mechanism according to claim 3 wherein said printing camprovides a support for a selected one of said type levers that movestoward the pivoted end thereof in effecting a printing and saidresetting cam provides a support for said selected one of said typelevers that moves back towards said one end thereof to effect a returnof said selected one of said type levers to a normal rotation.

6. The printing mechanism according to claim 1, wherein said printingpoint is coincident with an extension of said axis of rotation.

7. The printing mechanism according to claim 1, wherein said printingpoint is spaced radially a predetermined distance from an extension ofsaid axis of rotation.

1. A printing mechanism for serial data recording comprising: a platen;a printing point disposed in a given plane tangential to said platen;and a printing unit including a pot-shaped body of revolution having afirst hollow shaft extending therefrom in a direction away from saidprinting point and a cover for said body of revolution opposite saidfirst shaft adjacent said printing point, means coupled to said firstshaft to rotate said first shaft, said body of revolution and said coverabout an axis of rotation diSposed perpendicular to said given plane, aplurality of type levers disposed within said cover for rotationtherewith, each of said type levers having one end that is free formovement toward said printing point carrying type to be printed and theother end is pivotably mounted to said cover in a spaced radialrelationship with said axis of rotation, an opening in said coverdisposed coaxial of said axis of rotation and in a printing relationshipwith said printing point and said one end of each of said levers, and acam unit means disposed within said body of revolution in a cooperativerelation with said one end of each of said type levers to control themovement thereof so that a selected one of said type levers is movedfirst toward said axis of rotation and then passes through said openingparallel to said axis of rotation to strike said printing pointperpendicular to said given plane to effect a printing at said printingpoint, said cam unit means being adjustably mounted within said firstshaft by means of a second hollow shaft.
 2. The printing mechanismaccording to claim 1 wherein said cover includes guide slots directedradially to said axis of rotation for guiding said type levers throughsaid opening, and a type lever support track disposed concentricallyabout said axis of rotation for maintaining said type levers in a normalrotating position.
 3. The printing mechanism according to claim 1wherein said cam unit means includes a guideway concentrically disposedabout said axis of rotation, a printing cam and a resetting cam, each ofsaid printing cam and said resetting cam acts upon said one end of eachof said type levers in cooperation with said guideway to effect aprinting of a selected lever, said guideway being interrupted only at agiven location to enable type lever selection.
 4. The printing mechanismaccording to claim 3 wherein a selecting station is provided at saidgiven location for selecting desired ones of said type levers, andwherein control lines to said selecting station are led through saidsecond shaft.
 5. The printing mechanism according to claim 3 whereinsaid printing cam provides a support for a selected one of said typelevers that moves toward the pivoted end thereof in effecting a printingand said resetting cam provides a support for said selected one of saidtype levers that moves back towards said one end thereof to effect areturn of said selected one of said type levers to a normal rotation. 6.The printing mechanism according to claim 1, wherein said printing pointis coincident with an extension of said axis of rotation.
 7. Theprinting mechanism according to claim 1, wherein said printing point isspaced radially a predetermined distance from an extension of said axisof rotation.